Active control of large flexible structures in space requires the control of a very large dimensional system with one of substantially lower dimension. Modern modal control (MMC) has been developed previously to deal with this active structure problem ; however, control and observation spillover (as well as modelling error) can seriously degrade the controller performance by causing pole-shifts from the desired closed-loop locations. In this paper, the original MMC is enhanced by the addition of an innovations feedthrough term to the control law and a residual mode aggregation term to the state estimator. Under conditions presented the enhanced MMC can eliminate the observation spillover from critical residual modes ; hence, the spillover-induced pole shifting in these modes can be mitigated without changing the design of the original MMC. As shown, the trade-off is that the number of residual modes that can bo so enhanced is directly related to the number of available sensors